Variation of morphological traits in natural populations of maritime pine (Pinus pinaster Ait.) in Morocco

Abstract

Pinus pinaster Ait. is the main species used for reforestation in Morocco, both in mountain and low lands areas. However, little information is available about its intraspecific variation and adaptability in this range. This work studied the morphological variation of nine native populations, covering the distribution area of maritime pine in Morocco (Rif, Middle Atlas and High Atlas). Thirteen morphological and anatomical traits from cones (length and width), seeds (length, width, thickness and weight), seed wings (length and width) and needles (length, width, thickness and the number of stomata rows on the dorsal and convex faces of the needle) were measured in 232 trees. A Principal Component Analysis was used to explain the variation observed in four principal components related to cone (PCA3), seed (PCA1) and needle (PCA2 and PCA4) traits. Variability in morphological traits was high in Moroccan populations of maritime pine and significant differences among populations were found. Moreover, cone and needle traits showed clinal variation responding to latitude/altitude gradients. A hierarchical classification of all populations led to the formation of three major groups: (i) Mediterranean coastal populations, (ii) southeastern Rif, composed only by one population and (iii) the rest of populations, widely distributed through Moroccan maritime pine range. © INRA, EDP Sciences, 2006.